Interconnection structure with anti-adhesion layer

Abstract

A device comprises a first metal structure, a dielectric structure, a dielectric residue, and a second metal structure. The dielectric structure is over the first metal structure. The dielectric structure has a stepped sidewall structure. The stepped sidewall structure comprises a lower sidewall and an upper sidewall laterally set back from the lower sidewall. The dielectric residue is embedded in a recessed region in the lower sidewall of the stepped sidewall structure of the dielectric structure. The second metal structure extends through the dielectric structure to the first metal structure.

What is claimed is: 
     
       1. A device comprising:
 a first metal structure; 
 a dielectric structure over the first metal structure, the dielectric structure having a stepped sidewall structure, the stepped sidewall structure comprising a lower sidewall and an upper sidewall laterally set back from the lower sidewall; 
 a dielectric residue embedded in a recessed region in the lower sidewall of the stepped sidewall structure of the dielectric structure, the dielectric residue having a width decreasing as a distance from the first metal structure increases; and 
 a second metal structure extending through the dielectric structure to the first metal structure. 
 
     
     
       2. The device of  claim 1 , wherein when viewed in a cross section, the dielectric residue extends along a direction substantially perpendicular to a top surface of the first metal structure. 
     
     
       3. The device of  claim 1 , wherein the dielectric residue has a sidewall substantially aligned with an interface between the lower sidewall of the dielectric structure and the second metal structure. 
     
     
       4. The device of  claim 3 , wherein an upper portion of the sidewall of the dielectric residue is tapered. 
     
     
       5. The device of  claim 1 , wherein the dielectric residue has a different material than the dielectric structure. 
     
     
       6. The device of  claim 1 , wherein the dielectric residue comprises silicon nitride or silicon oxynitride. 
     
     
       7. The device of  claim 6 , wherein the dielectric structure comprises tetrathoxysilane (TEOS) oxide, an extreme low-k (ELK) dielectric material, or a nitrogen-free anti-reflective coating (NFARC). 
     
     
       8. The device of  claim 1 , further comprising:
 a silicon carbide layer between the first metal structure and the dielectric structure, wherein the second metal structure also extends through the silicon carbide layer. 
 
     
     
       9. The device of  claim 8 , wherein the dielectric residue has a bottom end higher than a top surface of the silicon carbide layer by a non-zero distance. 
     
     
       10. A device comprising:
 a non-insulator structure; 
 a dielectric structure over the non-insulator structure, the dielectric structure having a stepped sidewall structure, the stepped sidewall structure comprising a lower sidewall and an upper sidewall laterally set back from the lower sidewall; 
 a metal structure extending through the dielectric structure to the non-insulator structure, the metal structure having an upper metal portion confined by the upper sidewall of the dielectric structure, and a lower metal portion confined by the lower sidewall of the dielectric structure; and 
 an anti-adhesion material residue laterally between the lower metal portion of the metal structure and the dielectric structure, the upper metal portion laterally extending past opposite sides of the anti-adhesion material residue, wherein a bottommost position of the anti-adhesion material residue is higher than a bottommost position of the metal structure. 
 
     
     
       11. The device of  claim 10 , wherein the anti-adhesion material residue has a tapered top end. 
     
     
       12. The device of  claim 10 , wherein the metal structure has an inverted rounded corner connecting the lower metal portion and the upper metal portion. 
     
     
       13. The device of  claim 12 , wherein the anti-adhesion material residue forms a curved interface with the inverted rounded corner of the metal structure. 
     
     
       14. The device of  claim 13 , wherein the anti-adhesion material residue forms a linear interface with the lower metal portion, and the linear interface extends downwardly from the curved interface and terminates at a position higher than a bottom surface of the lower metal portion. 
     
     
       15. The device of  claim 10 , wherein the bottommost position of the anti-adhesion material residue is higher than a bottom surface of the dielectric structure. 
     
     
       16. The device of  claim 10 , wherein the dielectric structure is in contact with the anti-adhesion material residue at the bottommost position of the anti-adhesion material residue. 
     
     
       17. The device of  claim 10 , wherein the dielectric structure forms an interface with an entire bottom surface of the anti-adhesion material residue. 
     
     
       18. A device comprising:
 a first metal structure; 
 a dielectric structure over the first metal structure, the dielectric structure having a stepped sidewall structure, the stepped sidewall structure comprising a lower sidewall and an upper sidewall laterally set back from the lower sidewall; 
 a second metal structure extending through the dielectric structure, the second metal structure comprising a metal via laterally surrounded by the lower sidewall of the stepped sidewall structure of the dielectric structure, and a metal line laterally surrounded by the upper sidewall of the stepped sidewall structure of the dielectric structure; and 
 a dielectric residue located between the metal via and the lower sidewall of the stepped sidewall structure of the dielectric structure, and absent between the metal line and the upper sidewall of the stepped sidewall structure of the dielectric structure, wherein the dielectric structure forms an interface with an entire bottom surface of the dielectric residue at a position higher than a bottom surface of the metal via. 
 
     
     
       19. The device of  claim 18 , wherein the dielectric residue is inlaid in the lower sidewall of the stepped sidewall structure of the dielectric structure. 
     
     
       20. The device of  claim 18 , wherein the dielectric residue has a portion tapering upwardly.